【作者】 汪锰；

【导师】 谭立扬； 王树森；

【作者基本信息】 北京工业大学 ， 环境工程， 2001， 硕士

【摘要】 膜法富氧技术被发达国家称为“资源的创造性技术”。该技术系指利用空气中各组分透过膜的渗透速率不同，在压力差驱动下，将空气中的氧气富集起来的技术。它与深冷法、变压吸附法相比，具有设备简单，操作方便，节能显著，用途广泛等优点。然而将富氧膜投入较苛刻的工业环境中使用时，除了要求其具有较大的分离率和较高的透气率外还应具备较强的化学稳定性和热稳定性等。考虑到无机膜的特点和优势，我们认为研究和开发具有高选择性的微孔无机膜是解决富氧膜现存问题的一个重要途径。 目前通过常规方法制备而得的无机多孔膜孔径偏大，气体透过膜的机理受Knudsen扩散控制，因而这类多孔膜的分离率较低。理论和实验都已证明，只有将气体分离以Knudsen扩散控制为主的多孔膜改变为以分子筛分机理控制为主的分子筛膜，膜的分离率才能有较大幅度的提高。聚合物裂解法就是制备分子筛膜的一种新型方法，由这种方法所制膜的最可几孔径在1nm以下，其分离率比常规方法所制的无机膜有较大幅度的提高。 当前所研究的聚合物裂解膜主要有碳基裂解膜和硅基裂解膜。这两种膜的选择透过性能比较接近，但硅膜的抗氧化性远优于碳膜，所以硅分子筛膜更引起人们的重视。常规裂解膜的制备是将具有体型结构的硅树脂在高温含氧气氛下裂解，脱氢，脱碳，最后形成以SiOx为主要成分的骨架结构，骨架结构的间隙就构成膜孔。由于裂解用的常规甲基硅树脂膜，其大分子链是无规排列的，这就导致骨架结构间隙大小的不均一性，表现为膜孔的多分散性和分离气体时的低分离率。因此，选用立体规整结构的体型硅树脂膜作为先体进行控制裂解制膜，将使裂解膜孔径趋向均一，因而也就达到了提高分离率的目的。 本次实验就是由立体规整的硅树脂膜出发，经控制裂解从而获得孔径分布较窄，分离率较高的硅基裂解膜。考虑到一种新技术可推广实用的标志之一是其是否具有可重现性，所以我们通过大量条件实验，找到了影响膜制备的控制因素，使膜的制备方法已经基本成熟，膜制备具有很高的重现率。进而，我们将制备好的管式膜组装成一个小型膜装置将其应用于对实际气体的分离，考察单管膜组成膜装置后性能的衰减情况，从而为该技术的实用化提供实验依据。在此基础上，探讨了膜制备过程的反应机理，并将装置对实际气体分离后所得到的实验结果用适当的理论和模型加以诠释，从而为该技术的实用化提供理论参考。 实验表明这种制膜技术已经基本成熟，制备成品率可达80—90％。把成品膜组装成小型膜装置后对空气进行实际分离，经检测发现其富氧效果显著。例如在0.3MPa的压力下，富氧空气中氧含量可达41％，即将空气中的氧浓缩了2倍左右，而且通量达到了18.621/m~2d。 尽管从对单根管式膜与将其组装而得的小型膜装置在透气量和分离效果等方面的比较以及对膜装置的操作条件与工作效果关系的探讨来看，真正将该技术实用化还有一些亟待解决的问题。但该膜的制备工艺技成熟，制备膜所需的原料来源广泛且价格低廉，制备过程对设备无任何特殊要求且制作工艺简单易行，所以有理由认为它有广泛的工业化前景。更多还原

【Abstract】 Microporous inorganic membranes (rp0~~<1nm) have great potential for gas separation because of not only its good stability towards higher temperature and corrosive atmosphere but also its molecular sieve property. Typical molecular sieve microporous membranes are carbon-based (CMS) and silica-based structure (Si-MS). Because of the carbon-based structure, the CMS membranes are not suitable for hot oxygen environment, but Silica-based molecular sieve membranes can overcome the drawback and show an even higher selectivity and permeability. So, the investigators have paid more attention to the Si-MS . There are three typical methods to produce silicon-based membranes. They are sol-gel process ,CVD method and pyrolysis method .Comparing with the conventional membranes prepared by sol-gel and CVD methods, separation factors of pyrolysis membranes are much higher. In most cases, permeability of pyrolysis membranes are 10 times higher than the sol-gel and CVD membranes while the separation factors 1-3 times of the conventional membranes. Commonly, if you want to fabricate a pyrolysis Si-MS membrane, the precursor with stereo structure is made first, then the precursor is pyrolyzed, dehydrogenated and decarbonized in an activate atmosphere at high temperature, and finally the skeleton structure which main composition is S1Ox in final product is formed The gaps of the skeleton structure which constitute the pores of the resultant membranes are restricted to a rather lower level. An important reason is that the precursors of these membranes are polymerized by defunctional monomer. It means that the skeletons are composed of irregular arranged macromolecular chains and thus the gaps of the skeletons have random sizes, or, in other words, the pore sizes have a wilder distribution. In this work, we find a feasible way to meet our requirements. Firstly, a silicon resin material with regular molecular arrangement is polymerized by stereospecific polymerization process. Then a silicon molecular sieve membrane with much better permeability and permselectivity is made by pyrolyzing the polymeric resin. The high rate of terminal product which is as high as 80 90% is achieved by adopting the preparation technology that have been developed completely. At last an apparatus used for enriching oxygen is made from the membrane. Its working effect is remarkable, for example, the content of oxygen is 41% and the flux is 18.62l1m2d under the pressure of 0.3 Mpa. Furthermore, the preparation process of the membrane is simple, inexpensive and highly reproducible.更多还原